Process for removing odors from gases and air



Dec.v l0, 1929. J. T. TRAVERS PROCESS FOR REMOVING ODORS FIIOM GASES AND AIR Filed May 18. 1928 Jah CORPORATION OF OHIO This invention relates to a novelprocess for the removal of foul odors from gases and air. The process has speciiic reference to the removal ofnoxiousgases which are directly or indirectly the products of the put'refaction or decay of animal and vegetable proteins. These gases are produced in such industries as the manufacture of organic fertilizer, renderingv plants, reduction plants, packing 4 lo houses, garbage reduction plants and other kindredl industries.

.The chief odor producing compounds present in such noxious gases are mercaptans, putrescine, cadaverine, indole and scatole, 15 and it is to theremoval of these compounds that the process forming the subject matter of this invention, is principally directed.

In its more specific aspect, the process contemplates the treatment of the gases or air I with a treating mixture containing reagents capable of absorbing, adsorbing and reacting with the odor forming compounds present in the gases or air treated. rlihe treating mixture is preferably employed in the form j of a milk with which the gases to be treated are caused to physically contact for a time period sufficient to eiect the necessary adthe odors therefrom.

I am aware thatvarious processes have heretofore been devised for thepurpose of purifying gases, some of which are directed aol These prior art processes do not, however, in any instance contemplate the provision of 'a treating mixture or reagent capable of removing all of the several odor producing compounds above enumerated, which are variously found in the gases produced in such industrial plants as those mentioned.

It is the purpose of this invention to-provide a treating mixture for gases and` air which will be of more or less universal application and capable of removing from noxious odor producing compounds.

I am furthermore aware that certain of the prior art disclosures havecontemplated the employment of milk of lime solutions in the treatmentA of gases. While the treating .application med may is,

sorption, absorption and reaction to eliminate' ,f to .the removal of specificodors therefrom.

industrial gases any of the above enumerated JOHN T. TRAVERS, 0F COLUMBUS, OHIO, ASSIGNOR, BY DIRECT AND MESNE ASSIGN- MENTS, TO THE TRAVERS-LEWIS PROCESS CORPORATEON, OF COLUMBUS, OHIO, A

PROCESS FOR REMOVING ODORS FROM GASES ANID AIR 192e. serial no. 278,823.

mixture employed in my process is referred to as a milk, vthat is not to be confused with Matter insoluble in a solution of 1 part H2() to 1 part 1.19 specific gravity HC1 not less"- than 5%. 1 Total calcium carbonate and magnesium carbonate not less than 7 0% nor over 95%. Flotation value-the rate of settling in still water must be less than 4 inches per minute.

. lit has been found that marl concentrated to meet these specifications will contain the greater portion of the activated portions of the original marl. The activated portions of the original marl are 'due principally to I its content of cla in the process ofv decay. lt isa scientific act that clays, during the process of decay, have marked adsorptive and absorptive properties, and I havel ascertained that these roperties render such a concentrated marl lighly efficient in removing odor producing compounds from gases and air. It will be appreciated that a marlwhichfmeets with the first two qualifications set forth in the above specifications, may be' made to comply with the dotation value set forth in the specificatlons by segregating that so f portion of the marl which possesses the required flotation value and rejecting the remaining portions of the marl.

The composition of the treating mixture may be very elastic. The content of marl may vary between wide limits. For practical v y purposes the marl lcontent should not be less than 50% of the mixture, nor in excess of 80%, while the hydrated lime may vary from 15% to 35%, and ,the ferrous sulfate lfrom 5% to 15%. The hydrated lime content of the mixture should, however, always be in suiiicient excess to effect' a complete reaction with the ferroussulfate of the A'mixture when umn the mixture is incorporated in water to produce .a milk. An exemplary' composition which I have found to give excellent results and adapted to function eiiiciently over pro- 5 longed periods, is as follows Per cent Marl 7 0 Hydrated lime l 2O Ferrous sulfate or equivalent iron salt--- 10.

10 As above pointed out, this mixture is employed in the form of a milk which is produced by mixing a quantity of the mixture with water. The concentration of the milk may also vary between relatively wide limits. It will be appreciated, however, that the concentration should never be so great as to prevent a free flow of the milk.l The milk may be advantageously formed by mixing the treating mixture with water in the proportions of one part treating mixture to four parts of water. When formed in this manner,` the milk will flow freely. It will furthermore beappreciated that when the mixture has been incorporated in the milk, the calcium hydroxide and theferrous sulfate react forming calcium sulphate and ferrous hydroxide, which are present in the milk as such. The milk, therefore, contains the specially concentrated marl, calcium hydroxide and calcium sulphate and ferrous hydroxide, no ferrous sulfate being present as such in the treatingmilk. The ferrous hydroxide will become voxidized during thel operation of the process, but this does vnot lessen its effectiveness in the milk since ferrie Ahydroxide is fully as'eifective.

When air, or gases, containin mercaptans A are treated with the mixture a ove defined,

x czmsn plus Fe(on), =.(c,nsno (Femina,- j In the event that the gases or air treated and cadaverine, the reactions for which are the same, the reaction w ill be the following;-

. indole-and scatole, the reactions for'which are the same, are oxidized as follows Y.

The iruloxyl'producedv by the last reaction'- `is an odorless compound, soluble in an alka lng compounds'by virtue of its vadsorptiv 'plurality of verticall minute orices (5). The degree of anguing films on both the upper and lower surfaces of theb aiile members. It is highly im contain such putrefactive bases as putrescne vbe.l provided on the underneath `surfaceof The odor producing compounds such asf-'the gases' and kthe treating mixture occurs. atl

By the provision of a treating tower having baiiies of, this character, it will'be observed that theY gases arecompelled'to follow a circuitous path in their travel upwardly through the tower and to repeatedly contact with the f moving iilms of treating mixture. It will be observed lthat the inclination of the baille vmembers issuch as to compel the vgases or air/ line solution. Y

The specially concentrated marl combine or reacts with all these various odor produc and absorptive powers. It will thus be noted that the mixture employed in my process i capable of the removal from gases and air of any oneor all'of the. odor producing compounds hereinbefore enumerated which may be present therein.

Asv illustrative of a specific method for carrying 'outthe process formi-ng the subject matter of this invention, vreference will now be had to an apparatus suitable for practicing the process. Such an apparatus is diagrammatically illustrated in the accompanying drawings wherein:

Figure l is a'vieW in side elevationof the treating tower;

FigyQis. a detail view of one ofthe baiiles employed in the tower;

' The gases to be treated may be conveyed through a suitable conduit (l) controlled by a valve (2) into the lower end of a contact tower (3). The tower is provided with a disposed, inclined bailie members (4). ach of these baille membersis provided with a multiplicity of larity and the size 0f the orifices in the baiile members' are important factors, since approximately vof the adsorption, absorption and reactions occur during the Contact of the gases with the iilms on the underside 0f the hailies. y

The angularity. of the bailles and the ori5. fices therein, should be such that the treating mixture which may be supplied to the tower through the line (6)-, will form in thin movportant' that the arrangement of the baiiies beisuch that a thin moving film of liquid will' each bame, since the greatest contact'between` these points within the treating tower (3)1 rising through the tower to sweep downwardly following each successive contact with a baie member, thus compelling a prolonged intimate contact between the gases and the films moving over the under-surfaces of the baiiie members. The gases or air in passing through one baliie to the space beneath the next succeeding baille must pass through the liquid cascading from one baiiie to the next lower bae in the tower. It will be apparent that the ases have successive contacts with moving films f the treating mixture and that the gases are scrubbed intermediate each film contact by passage throu h the cascading liquid treating mixture. he gases, subsequent to passage through the. tower, pass through the outlet (7) and the flow of the gases through the tower may be accelerated y the employment of a suitable suction device such as indicated at (8).

The treating liquid may be advantageously led from the lower end of the tower through the line (9) to a suitable sump (10) and again returned from the sump to the treatingvtower via the line (11) controlled by the valve (12) and the pump (13) which delivers the liquid treating mixture to the inlet line (6).

In the practice of the process, it will be found that the treating milk composition will be eiective for the removal of odor producing compounds from gases and air or'exceedingly prolonged periods. This is partially due to the fact that the adsorptive, reactive powers of the treating milk composition are exceptionally high and further due to the fact that the odor producing compounds, while adequate to seriously contaminate the atmosphere surrounding an in-` dustrial plant where they are produced, are,

Y in reality, present in very small amounts.

The relatively insignificant cost of the treat'- iug mixture does not render its replacement uneconomic and furthermore entirely eliminates the practical necessity for regenerating lthe same.

By the term suitably concentrated marl, as used in the appended claims it is to be understood that'I mean a marl meetin with the s ecicat-ions hereinbefore set fort at I claim for my invention is 1. A process for lthe removal from air and gases of the foul odors of indole, scatole, putrescine, cadaverine and mercaptans present in the air or gas either individually or collectively, comprising passing the contaminated air or gas in physical contact with atreating composition characterized by its content of a suspension of a suitably concentrated marl.

"2. A rocess for the removal from air and gases o the foul odors of indole, scatole, putrescine, cadaverine, and mercaptans pres-l ent in the air or gas either individually or collectively, comprising passing the contaminated air or gas in physical contact with a absorptive and treating composition characterized by its content of a suspension of a suitably concentrated -marl and a substantial content of calcium hydroxide.

3. A. rocess gases o putrescine, cadaverine, and mercaptans present in the air or gas either individually or collectively comprising passing the contamifor the removal from air and nated air or gas in physical contact with a,

treating composition characterized by its content of a suspension of a suitably concentrated marl, a substantial content of calcium hydroxide and a substantial content of calcium sulphate.

4. A rocegss for the removal from air and gases o the -foul odors of indole, scatole, putrescine, cadaverine and mercaptans present in the air or gas either individually or collectively, comprising passing the contaminated air or gas in physical contact with a treating composition characterized by its content of a suspension of a suitably concentrated marl, a substantial content of calcium hydroxide, a substantial content of calcium sulphate and substantial content of the hydroxides of iron. 4

' JOHN T. TRAVERS.

the foul odors of indole, scatole, 

